The present invention relates to a technique for expanding a dynamic range of an output detection circuit in high frequency power amplifying electronic parts (RF power module) with a high frequency power amplifier built therein and enhancing controllability of output power, and to a technique effective if applied to, for example, an RF power module used in a cellular phone and a wireless communication device using the same.
An RF power module having built therein a high frequency power amplifier (PA) in which transistors such as MOSFETs (Metal Oxide Semiconductor Field-Effect-Transistor), GaAs-MESFETs, etc. is incorporated in a transmission output section of a wireless communication device (mobile communication device) such as a cellular phone, etc.
In a cellular phone, a system is generally configured in such a manner that a phone call is made while output power is changed in accordance with transmission power indication information sent from a base station so as to adapt to an ambient environment and interference is avoided between the cellular phone and other cellular phones. In a GSM (Global System for Mobile Communication) type cellular phone, for example, an output power detection signal and an output level indication signal Vramp outputted from a baseband circuit are compared with each other by an APC (Automatic Power Control) made up of an error amplifier and the like to thereby generate a control voltage Vapc for controlling the output power.
Then, the gain of each amplifying stage of a high frequency power amplifier of a transmission output section has been controlled by a bias circuit so as to reach output power necessary for a call by the control voltage Vapc.